The Allegheny Neuropsychiatric Survey (MH45311) investigates the neuropsychological, psychosocial, and neurological consequences of HIV infection and AIDS among community residents seeking primary medical care with Allegheny County (PA). The purpose of this revised application is to seek continuation of funding in order to study, in detail, Minor Cognitive Motor Disorder (MCMD). The proposed extension will recruit an additional 160 HIV+subjects with AIDS, and 50 HIV- controls. The HIV+subjects will be evaluated every six months for three years, or until they are diagnosed with HIV-associated dementia (HAD). The intensive evaluations will study the cognitive, neurological, and psychosocial status of these individuals. Magnetic Resonance Imaging studies will evaluate the structural and functional integrity of the CNS. Plasma viral load (and a selected sample of CSF viral load) will indicate peripheral (and CNS) infection status. These data will be analyzed to address three specific questions: 1) what is the reliability of the diagnosis of MCMD?, 2) what are the neurobehavioral characteristics of patients with MCMD?, and 3) what factors are associated with transition points around MCMD; that is, what predicts transition from normal cognition to MCMD, and from MCMD to HIV- associated dementia? These data will address four linked hypotheses: 1) that MCMC can be reliably diagnosed, 2) that its hallmark is psychomotor slowing, 3) that the transition into MCMD is preceded in time by functional changes in the CNS, and 4) that MCMD and HAD are independent syndromes. These data will provide important information about the course of the cognitive impairment in HIV/AIDS. By studying MCMD in detail, and the factors that predict transition to MCMD and HAD, it may be possible to provide information useful to the development of rational treatment strategies directed at cognitive dysfunction.